Mobile devices, such as mobile phones and other hand-held devices, are typically available with various applications and functions. For example, conventional mobile devices, such as mobile phones and other hand-held devices, are capable of receiving and/or sending text messages. The ability to send and receive text messages provides mobile phone users with the ability to exchange short messages without having to establish a voice call.
Short Message Service (SMS)
Short Message Service (SMS) is a service that enables users to exchange short text messages (SMS messages) of up to 256 bytes over a communications network. SMS is characterized by out-of-band packet delivery and low-bandwidth message transfer, which results in a highly efficient means for transmitting short bursts of data. SMS messages can originate from various sources, in various ways, such as by using a user terminal such as a mobile phone or other hand-held device that is configured to exchange SMS messages. Final destinations for SMS messages are also not limited to hand-held devices and could include e-mail addresses and fax machines.
SMS is a store and forward service, i.e., SMS messages are not sent directly from sender to recipient, but always via a Short Message Service Center (SMSC) described below. The SMSC handles and manages the SMS messages.
SMS enables an active mobile phone to receive or submit a short message at any time, independent of whether a voice or data call is in progress. SMS messages are exchanged independently of each other, and as such, SMS communication does not require the establishment of a simultaneous and contiguous end-to-end traffic path.
SMS also guarantees delivery of the SMS message by the network. Temporary failures due to an unavailable receiving (destination) device can be identified, and the SMS message can be stored in the SMSC until the destination device becomes available.
SMS also enables receipt notification of SMS messages. After the destination device has received the SMS message, an acknowledgement indicating the SMS message has been delivered is returned to the sender.
A terminal configured for SMS provides the user with methods to compose, edit, send, receive, read, and delete messages. Whenever an SMS capable terminal is registered to a network, it is capable of exchanging SMS messages, even when the terminal is engaged in a voice or data call. If the intended destination is not available or does not acknowledge delivery, any number of message handling routines may be initiated, including re-transmitting the message at periodic intervals or discarding the message.
Base Station (BS)
The basic network architecture of a conventional communications network utilizing SMS is shown in FIG. 1. The network serves as the communications medium for the messages and provides a system for exchanging SMS messages. Various types of data, such as SMS messages, voice calls, photos, and other multimedia files, can be exchanged between a mobile phone or other communication device and a base station (BS). The base station controls the radio signals of one or more communication devices within a given range surrounding the base station.
Mobile Switching Center (MSC)
A Mobile Switching Center (MSC) performs the switching functions of the network and controls calls to and from various telephone and data systems. The MSC delivers and receives the SMS messages to and from mobile device users through the proper base stations.
Home Location Register (HLR) and Visiting Location Register (VLR)
Location registers supplement MSCs with information about the users. The MSC interacts with a Home Location Register (HLR), which is a database used for permanent storage and management of subscriptions and service profiles. Each user is associated with a single HLR, which retains the user's record. The HLR is maintained by the cellular service provider associated with the particular MSC. The HLR provides routing information, e.g., user information, including address, account status, and preferences, for an indicated user.
The MSC also interacts with a Visiting Location Register (VLR), which maintains temporary user information (such as current location) to manage requests from users (roamers) who are out of the area covered by their home system. Information on roamers is obtained from each roamer's home HLR.
When a MSC detects a mobile user's presence in the area covered by the particular MSC, the MSC first determines if the user is in their home area or is roaming, i.e., the user is a visitor. When the user is in their home area, the HLR associated with the MSC has the necessary information for initiating, terminating, or receiving a call. When the user is roaming, the VLR contacts the user's HFLR to get the necessary information to set up a temporary user profile.
The user's location is recorded in the HLR, and if the user is roaming, the user's location is also recorded in the VLR.
If the user is in their home area and wants to initiate a call or send a message, the MSC contacts the HLR prior to setting up the call. If the user is roaming and wants to initiate a call or send a message, the MSC contacts the VLR prior to setting up the call.
If the user is in their home area and there is a call or message for the user, then the call or the message goes to the home MSC and the home MSC delivers the call immediately. If the user is roaming and there is a call or message for the user, the home MSC contacts the VLR to determine the appropriate route to deliver the arriving call and then transfers the call to the roaming area MSC. Also, if the destination device is not available when message delivery is attempted, the HLR for the destination device informs the MSC when the destination device is recognized as accessible by the mobile network, and thus the message can be delivered.
Short Message Service Center (SMSC)
A Short Message Service Center (SMSC) is a message center (MC) that relays SMS messages through the network. The SMS message is sent through the communications network via the MSCs and is received and stored by the desired SMSC. After being relayed to a desired SMSC, the SMSC stores and forwards the SMS messages. The SMSC determines if the intended destination device of the message is available to the network, and if so, the message is then sent to that destination device. Whenever an SMS-capable terminal is registered to a network, it is capable of exchanging SMS messages, even when the terminal is engaged in a voice or data call. If the intended destination is not available or does not acknowledge delivery, the SMSC may then initiate any number of message handling routines including re-transmitting the message at periodic intervals or discarding the message.
SMS messages include several elements in addition to the text of the message. An SMS message can include information regarding, for example, a validity period for specifying how long the message remains valid before the SMSC will delete it; a time stamp for allowing the SMSC or the sender to track and control individual messages; a data coding scheme for indicating how the data is encoded within the message; a source and destination address of the message; and an address of the SMSC that handles the message.
External Short Message Entity (ESME)
An External Short Message Entity (ESME) is a network element external to a wireless carrier's network that can facilitate the reception and transmission of SMS messages via the SMSCs from an external source. The ESME typically represents a fixed network SMS client, such as a WAP Proxy Server, E-Mail Gateway, Voice Mail Server (VMS), Web-based messaging service, or e-mail integration service.
The VMS is responsible for receiving, storing, and playing voice messages intended for a user that is busy or not available to take a voice call. It is also responsible for sending voice-mail notifications for those users to the SMSC.
The web-based messaging ESME supports interconnections to the World Wide Web for the submission of messages and notifications.
The E-Mail Gateway delivers e-mail notifications and supports two-way e-mail, using an SMS-compliant terminal. The SMSC connected to this ESME must support interconnection to e-mail servers acting as message input/output mechanisms.
There are several other ESMEs which may submit SMS messages to the SMSC, and include, but are not limited to, paging networks, and specialized software for PC-based messaging.
Short Message Peer-to-Peer (SMPP) Protocol
The Short Message Peer-to-Peer (SMPP) protocol is an open industry standard messaging protocol that is widely deployed in the mobile telecommunications industry to simplify integration of data applications in the wireless mobile network.
The SMPP protocol provides a flexible data communications interface for the transfer of SMS messages between the ESMEs and MCs by establishing an SMPP session.
The SMPP protocol provides a means for the SMSC to transfer the SMS message to the MSC that serves the destination device. Furthermore, after the address of the MSC has been obtained, the SMPP protocol provides a confirmed delivery service.
Routing Entity (RE)
A Routing Entity (RE) is a network element that is used to route messages between MCs and between ESMEs and MCs. The RE has the ability to emulate the functionality of both an MC and an ESME so that to an ESME, the RE acts as an MC, and to an MC, the RE acts as an ESME. The REs are used to hide a network of MCs, thereby presenting only the REs as the external interface point for the ESMEs.
An SMPP Gateway is a type of RE that serves as a concentrated point of access for allowing multiple ESMEs to connect to an SMSC.
Mobile-Originated (MO) Messages
A conventional method for sending SMS messages originating from a mobile device is described as follows. The SMS message can be delivered to a destination device which is not limited to a mobile device.
When the mobile device is powered on, it automatically registers with the wireless network via the HLR. After the mobile device user generates an SMS message and executes a send operation using the mobile device, the SMS message is delivered to the base station and then to the MSC. The MSC sends the SMS message to the SMSC, and the SMSC delivers the SMS message to the ESME via the SMPP Gateway. The ESME then forwards the SMS message to the appropriate receiving device. The SMSC acknowledges to the MSC the successful outcome of the message transfer, and the MSC subsequently returns the outcome of the operation to the message-originating mobile device.
Mobile-Terminated (MT) Messages
A conventional method for receiving SMS messages terminating at a mobile device is described as follows. The SMS message can originate from a device which is not limited to a mobile device.
The SMS message received in the ESME is transferred to the SMSC via the SMPP Gateway. The SMSC then interrogates the appropriate HLR and receives the routing information for the mobile device user to whom the message is directed. The SMSC sends the SMS message to the MSC, which retrieves user information from the HLR. The MSC then transfers the SMS message to the mobile device user, and returns to the SMSC the outcome of the operation, e.g., successful or failed delivery. If message delivery by the SMSC fails due to a temporary failure, e.g., the mobile device being unregistered, the SMS message is stored in the SMSC, and the SMSC requests the HLR to notify the SMSC when the indicated mobile device becomes available. If requested by the ESME, the SMSC returns a status report indicating delivery of the SMS message.
Incoming SMS messages can be stored in an application running on the mobile device, such as an SMS Inbox.
Instant Messaging (IM)
The ability to send and receive text messages using SMS is a popular function in mobile devices. Another message service is Instant Messaging (IM), a PC-based on-line messaging service that provides quick communication over the Internet via text messages, i.e., “instant messages.” IM must be subscribed to separately from SMS. There are several IM services that each have an established community of users.
IM allows a user to maintain a list of people, e.g., “buddy list” or “contact list”, with whom to interact. The user can exchange messages with any person on the contact list, thereby allowing for constant peripheral contact with family, friends, and co-workers. Sending an instant message opens up a small window in the user interface of each of the two communicating users where the users can type messages for viewing by both users. When two users are sending instant messages to each other, the users have established a “conversation”. All of the messages sent during the conversation are displayed in each user's user interface so that each user may view the previously transmitted (sent or received) messages. There may be a maximum limit to the number of previously transmitted messages displayed on the user interface.
IM Incompatibility
IM service providers, e.g., AOL, MSN, and Yahoo, provide separate IM services, e.g., AOL Instant Messenger, MSN Messenger, and Yahoo Messenger, respectively, which each use a proprietary protocol which is not understood by the other IM service providers. It is necessary to log in to each IM service separately, so that each user must maintain separate contact lists, settings, and other information for each IM service. Thus, each of the IM service providers require a separate application corresponding to the IM service(s) that will be run on the user's PC or mobile device.
Most of the popular IM services provide a variety of features, other than the ability to send instant messages, e.g., exchanging web links, images, sounds, and other types of files by sending them directly to other users.
Mobile Instant Messaging (MIM)
In order to be able to establish direct communication between SMS users and IM users, wireless service providers have established a system for allowing SMS users to connect to IM services. Mobile device users can send and receive SMS messages on their mobile devices to log in to an IM service and then send instant messages to PC or other mobile device users who are logged in to the same IM service.
Mobile Instant Messaging (MIM) is a messaging service that allows users to log in to an IM service using their mobile devices. However, in conventional mobile devices, users must download onto their mobile devices separate applications for each IM service. Therefore, the ability to use more than one MIM service provider requires a large amount of memory in the user's mobile device, since the user must download and run separate applications for each IM service.